The only way you can "convert" .toast files to .mp4 files is if there are actually MPEG-4 files on the Roxio Toast compilation in the first place. If that is the case, you can simply load the file using Roxio Toast Titanium, open the compilation and export the .mp4 files.
Convert Roxio Toast disk image file to MPEG-4 video file format.
We found one software available in the database for this conversion.
Apple macOS / Mac OS X software - convert toast to mp4 on OS X
Roxio Toast 11 Titanium makes disc burning, DVD copying and video conversion as easy as drag, drop and go.
Convert from toast file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.